Anti-UPB1 (aa 287-336) polyclonal antibody

Objective: Dihydropyrimicline dehydrogenase (DPD) deficiency accounts for approximately 43% of grade 3-4 toxicity to 5-fluorouracil. There, however, remain a number of patients presenting with 5-fluorouracil-associated toxicity despite normal DPD enzyme activity, suggesting possible deficiencies in clihydropyrimidinase (DHP), encoded by the DPYS gene, and/or beta-ureidopropionase (BUP-1), encoded by the UPB1 gene. This study investigates the role of DPYS sequence variations in individuals with unexplained molecular basis of altered uracil catabolism. Methods: This study included 219 asymptornatic healthy volunteers with known DPD enzyme activity and [2-C-13]- uracil breath test (UraBT) profiles. All samples were genotyped for sequence variations in the DPYS gene using denaturing high-performance liquid chromatography (DHPLC) and Surveyor enzyme digestion with confirmation by direct sequencing. Site-directed mutagenesis and expression analysis were performed to determine the effect of the identified nonconservative mutations on DHP enzyme activity. Results: Seven previously reported and 11 novel sequence variations were identified, including three nonconservative mutations; two of which (L7V and 1635delC) demonstrated decreased DHP activity when expressed in the RKO cell line (P= 0.25). The P values were not significant due to the small sample size (n=3); however, a modified [2-C-13]- uracil breath test, the C-13-dihydrouracil breath test, was administered to four volunteers to confirm that the 1635delC mutation does in fact reduce in-vivo DHP activity. Conclusion: Data presented in this study demonstrate that alterations of uracil catabolism are not limited to DPD deficiency, and that inactivating mutations in DHP might impair uracil catabolism in cases of normal DPD activity.

beta-Ureidopropionase (beta UP) deficiency is an autosomal recessive disease caused by abnormal changes in the pyrimidine-degradation pathway. This study aimed to investigate the mutation of beta-ureidopropionase gene (UPB1) gene and clinical features of 7 Chinese patients with bUP deficiency. We reported 7 Chinese patients with bUP deficiency who were admitted at Tianjin Children's Hospital. Urine metabolomics was detected by gas chromatography-mass spectrometry (GC-MS). Then genetic testing of UPB1 was conducted by polymerase chain reaction (PCR) method. The patients presented with developmental delay, seizures, autism, abnormal magnetic resonance imaging, and significantly elevated levels of N-carbamyl-beta-alanine and N-carbamyl-beta-aminoisobutyric acid in urine. Subsequent analysis of UPB1 mutation revealed 2 novel missense mutations (c.851G>T and c.853G>A), 3 previously reported mutations including 2 missense mutations (c.977G>A and c.91G>A) and 1 splice site mutation (c.917-1G>A). The results suggested that the UPB1 mutation may contribute to bUP deficiency. The c.977G>A is the most common mutation in Chinese population.